The Spanish attempt to subjugate the Incan Empire just like in the original timeline. However, both sides are completely immune to disease and the Incans do not have a civil war in the years leading up to the Spanish invasion.
Can the Incans fight off the Spanish invaders?
Or will the forces of Spanish imperialism prevail regardless?
Let us say that Spain is allowed to invade with everything without worrying about France or other European powers taking advantage of the military absence. Assume that just like in OTL, the Spanish have already taken over the Aztecs (and for some reason, the Aztecs did not have the disease immunity condition).
How do you think the war would go down? Please explain.